As an inner liner structure of tires, a three-layered structure is known that is formed by a resin film layer (film layer) 10, an adhesive layer 11 and a butyl inner layer (rubber layer) 12 as illustrated in FIG. 1. In this case, a rubber composition that is mainly composed of butyl rubber, halogenated butyl rubber, and so on is used for the butyl inner layer 12, which is disposed on the inner surface of the tire as an air barrier layer to maintain the inner pressure of the tire. In addition, a known technique utilizes a film that is composed of a thermoplastic resin and a thermoplastic elastomer as the resin film layer 10. Moreover, a variety of materials have been considered as candidates for the adhesive layer 11 (see, for example, JP 7-082418 A (PTL 1) and JP 2007-098843 A (PTL 2)).
Since the aforementioned three-layered, inner liner structure involves the resin film layer 10 and the butyl inner layer 12, the resulting tire would have high resistance to air permeability, but may be heavy in weight.
To address such a deficiency, studies have been made to reduce the weight of the tire by removing the butyl inner layer 12 and a squeegee layer 13 (FIG. 2).
In this context, a known technique allows a resin film layer 20 to be adhered to a carcass cord layer 22 by applying a commercially available adhesive, such as METALOCK R-46 (manufactured by Toyo Chemical Co., Ltd.) and Chemlok 6250 (manufactured by LORD Corporation), to the resin film layer 20 or the carcass cord layer 22.
However, an adhesive layer 21 formed by the aforementioned commercially available adhesive has low tackiness due to the reaction of adhesive components in the adhesive layer 21, making it difficult to improve both adhesiveness to the resin film layer 20 and adhesiveness to the carcass cord layer 22. This results in insufficient adhesiveness between the resin film layer 20 and the carcass cord layer 22 and peeling off of the resin film layer 20 from the carcass cord layer 22, interfering with stable production of tires and causing separation of the resin film layer 20 under high-load running conditions.
There is another requirement to use more environment-friendly adhesives without lead, halogen, and so on.
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